Bahraini authorities say two policemen have been killed and six injured in a bomb attack south of the capital.

The Interior Ministry said on its Twitter feed on Tuesday that the officers were killed in a "terror blast" in the largely Shiite community of Sitra.

It says one of the surviving officers was seriously wounded, while five others suffered minor to moderate injuries.

Bahrain is a Sunni-ruled kingdom that is home to the U.S. Navy's 5th Fleet. It continues to face low-level unrest more than four years after a Shiite-dominated opposition movement took to the streets to demand greater political rights.

Anti-government activists have planted bombs that have killed or maimed police in the past.